I have a Yaesu FT-7 transceiver that seems to generate the proper output, but the receiver is behaving strangely ...

Q Rob, WA4RX, asks, “I have a Yaesu FT-7 transceiver that seems to generate the proper output, but the receiver is behaving strangely. Sometimes it seems to die altogether. When I jostle the rear cabling and PL-259 it comes back in full force. Gently tapping the radio provides similar results. I’ve checked the coax and it is fine; so is the PL-259 connection. This has occurred on different antennas and cables, so I know it’s not the cable system. Have you heard of such a problem before?”

AThis is a common problem on older radios. There are three possible causes:

1. Oxidation on the connectors (using a contact cleaner would help here).
2. Fatigue of the contact “fingers” on the center receptacle of the SO-239 coaxial connector. After repeated connects/disconnects, the sides of the center part of the SO-239 are often bent outward, resulting in poor contact with the pin on the PL-259. You can sometimes take a sharp probe and bend them slightly inward to correct this. If the connector doesn’t look too difficult to replace with a new one, you might want to consider that approach.
3. Cold/fatigued solder joint on the inside of the radio at the SO-239 connector.

From QST November 1999